US20090161636A1 - Flexible control channels for unplanned wireless networks - Google Patents

Abstract

A wireless node configured to communicate with a remote node using a timeslot structure. The timeslot structure includes a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units. The wireless node is further configured to assign any one of a plurality of control messages for the data channels to any one of the control units.

Description

BACKGROUND
• 1. Field
• This disclosure relates generally to wireless communication and more specifically, but not exclusively, to flexible control channels for unplanned wireless networks.
• 2. Introduction
• A wireless communication system may be deployed in various ways depending on the requirements of the intended application. For example, a planned deployment may be utilized for an application such as a cellular network where seamless connectivity is desired over a relatively wide area. To reduce interference in such a network, the channel or channels used by the wireless devices of the network may be defined throughout the network.
• Recently, there has been an increasing trend towards low-cost, flexible deployment of wireless networks to support local area networks for indoor cellular usage and home access points. As a result, system design has moved away from the planned and smooth interference model to one that needs to be more robust to (1) bursty interference due to partial loading and (2) service through an access point that may not be the best from an RF link perspective. This leads to greater uncertainty in the design with regard to the lowest signal-to-interference noise ratios (SINRs) that can be achieved as well as the extent of traffic multiplexing that takes place. While data transmissions in such a setting have traditionally been taken care of through dynamic interference avoidance, rate adaptation, and hybrid automatic repeat-request (ARQ) techniques, control transmissions do not enjoy the benefits of those techniques.
• Accordingly, there is a need in the art for improvements in control transmissions to enable greater robustness as needed as well as flexibility to traffic demands.
SUMMARY
• In one aspect of the disclosure, an apparatus for wireless communications includes a processing system configured to communicate with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, the processing system being further configured to assign any one of a plurality of control messages for the data channels to any one of the control units.
• In another aspect of the disclosure a method of communications includes communicating with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units and each of the control units is capable of carrying any one of a plurality of control messages for the data channels, and assigning one of the control messages to one of the control units.
• In yet another aspect of the disclosure, an apparatus for wireless communications includes means for communicating with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, and means for assigning any one of a plurality of control messages for the data channels to any one of the control units.
• In a further aspect of the disclosure, a computer-program product for wireless communications includes a machine-readable medium comprising instructions executable by a processing system to communicate with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, and assign any one of a plurality of control messages for the data channels to any one of the control units.
• In yet a further aspect of the disclosure, an access terminal for wireless communications includes a processing system configured communicate with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, the processing system being further configured to assign any one of a plurality of control messages for the data channels to any one of the control units, and a user interface configured to enable a user to control communications between the processing system and the remote node.
• In another aspect of the disclosure, an access point includes a wireless network adapter configured to support a backhaul for a remote node to a network, and a processing system configured to communicate with the remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, the processing system being further configured to assign any one of a plurality of control messages for the data channels to any one of the control units.
• It is understood that other aspects of the invention will become readily apparent to those skilled in the art from the following detailed description, wherein various aspects of the invention are shown and described by way of illustration. As will be realized, the invention is capable of other and different configurations and implementations and its several details are capable of modification in various other respects, all without departing from the scope of this disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
• Various aspects of a wireless communications system are illustrated by way of example, and not by way of limitation, in the accompanying drawings, wherein:
• FIG. 1 is a conceptual diagram illustrating an example of awireless network100;
• FIG. 2 is a conceptual diagram illustrating an example of a timeslot structure to support communications between two wireless nodes in a wireless network;
• FIG. 3 is a conceptual diagram illustrating an example of a timeslot structure to support asymmetric data flows between two wireless nodes in a wireless network;
• FIG. 4A is a conceptual diagram illustrating a more detailed example of a timeslot structure to support asymmetric data flows between two wireless nodes in a wireless network;
• FIG. 4B is a conceptual diagram illustrating an example of a timeslot structure to support a change back to a symmetric data flow between two wireless nodes in a wireless network;
• FIG. 5 is a conceptual diagram illustrating an example of a jammer situation that can occur in a home access point (HAP) setting;
• FIG. 6 is a conceptual diagram illustrating an example of a timeslot structure to support jammer avoidance mode of operation;
• FIG. 7 is a conceptual diagram illustrating an example of a control channel configured as an OFDM symbol;
• FIG. 8 is a block diagram illustrating an example of the functionality of a wireless node; and
• FIG. 9 is a block diagram illustrating an example of the functionality of a processing system.
DETAILED DESCRIPTION
• Various aspects of the disclosure are described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative. Based on the teachings herein one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. Furthermore, an aspect may comprise at least one element of a claim.
• FIG. 1 is a conceptual diagram illustrating an example of awireless network100. Thewireless network100 is shown with several wireless nodes102. A wireless node may receive, transmit, or both. In the discussion that follows, the term “receiving node” may be used to refer to a wireless node that is receiving and the term “transmitting node” may be used to refer to a wireless node that is transmitting. These designations do not imply that the wireless node is incapable of performing both transmit and receive functions.
• A wireless node may function as an access point, a relay point, an access terminal, or any combination thereof. In the example shown inFIG. 1, a number of thewireless nodes102A-102B function together to provide backhaul services to a number of access terminals102C. Thenetwork100 includes awireless node102A that functions as an access point by providing an interface to another network (e.g., a cellular network, an Internet service provider (ISP), the Internet, etc.) (not shown). Thenetwork100 also includes two wireless nodes102B₁and102B₂that function as relay points to connect the access terminals104C to theaccess point102A.
• Theaccess point102A may use one of many different wireless access protocols to support radio communications with the relay points102B and access terminals102C. By way of example, theaccess point102A may support Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), 802.11, or any other suitable access protocol. Theaccess point102A may also support the same or different access protocol with another network (e.g., a cellular network, an Internet service provider (ISP), the Internet, etc.) (not shown). By way of example, theaccess point102A may provide an 802.11 interface to the relay points102B and access terminals102C and provide an EV-DO interface to the other network. The actual wireless access protocols employed for any particular network will depend on the specific application and the overall design constraints imposed on the system.
• Four access terminals102C are shown inFIG. 1. In this example, two access terminals102C₁and102C₂are connected to theaccess point102A through the relay point102B₁, one access point102C₃is connected to theaccess point102A through the relay point102B₂, and one access point102C₄is connected directly to theaccess point102A. The connections between theaccess point102A and the access terminals102C may be dynamically reconfigured based on any number of relevant factors (e.g., loading, failures, mobility, etc.). In some configurations of thewireless network100, an access terminal102C may be connected to theaccess point102A through multiple relay points102B or support multiple flows (e.g., telephony, messaging, etc.) through one or more relay points102B. As an example of the latter, a first flow between theaccess point102A and the access terminal102C₂may be routed through the relay point102B₁and a second flow between theaccess point102A and the access terminal102C₂may be routed through the relay point102B₂.
• In some configurations of thewireless network100, the flows between wireless nodes may be maintained using a time division multiplexing scheme. By way of example, each wireless node102 in thenetwork100 may be assigned designated timeslots to transmit and receive. For instance, theaccess point102A may transmit to the access terminal102C₄during odd numbered timeslots and the access terminal102C₄may transmit to theaccess point102A during even numbered timeslots. Similarly, theaccess point102A may transmit to the relay points102B₁and102B₂during odd numbered timeslots and the relay points102B₁and102B₂may transmit to the access terminals102C₁,102C₂, and102C₃during even numbered timeslots
• FIG. 2 is a conceptual diagram illustrating an example of a timeslot structure to support communications between two wireless nodes in a wireless network. In this example, transmissions from a first wireless node to a second wireless node are designated by202A, and transmissions from the second wireless node to the first wireless node are designated by202B. More specifically, thetimeslot structure204A shown intimeslot1 represents a transmission from the first wireless node to the second wireless node, thetimeslot structure204B shown intimeslot2 represents a transmission from the second wireless node to the first wireless node, thetimeslot structure204C shown intimeslot3 represents a transmission from the first wireless node to the second wireless node, and thetimeslot structure204D shown intimeslot4 represents a transmission from the second wireless node to the first wireless node.
• Each timeslot includes threedata channels206A-206C and threecontrol channels208,210 and212. The control channels may be used to provide control messages for the information carried in thedata channels206A-206C. In the following example, the control messages will be described in terms of a request/grant scheme to support a transmission from the second wireless node to the first wireless node intimeslot4.
• Intimeslot1, one or more wireless nodes in the network intending to receive data intimeslot4 transmit a resource utilization message (RUM). By way of example, and with reference toFIGS. 1 and 2, the relay point102B₁may intend to schedule to receive from the access terminal102C₂at the same time the relay point102B₂intends to schedule to receive from the access terminal102C₃. Depending on the distance between the relay point102B₂and the access terminal102C₂and the transmission power of the access terminal102C₂, a transmission from the access terminal102C₂may interfere with the reception at the relay point102B₂. In that event, relay point102B₂may transmit a RUM on one of thecontrol channels208,210 and212 before the scheduled transmissions to indicate to other transmitting nodes that it desires a collision avoidance mode of transmission to mitigate interference. In some configurations, a RUM may be weighted to indicate not only that a receiving node is disadvantaged (e.g., due to the interference it sees while receiving), but also the degree to which the receiving node is disadvantaged. A transmitting node that receives a RUM may utilize the fact that it has received a RUM, as well as the weight thereof, to determine an appropriate response. By way of example, if the access terminal102C₂determines that the relay point102B₂is more disadvantaged than the relay point102B₁, access terminal102C₂may elect to abstain from transmitting or may reduce its transmit power to avoid interfering with the relay point102B₂. Alternatively, in the event the access terminal102C₂determines that its own relay point102B₁is more disadvantaged than the relay point102B₂(or any other receiving nodes that sent RUMs), the access terminal102C₂may ignore the RUMs from the other nodes. In that case, the access terminal102C₂may elect to transmit.
• In the foregoing example, if the access terminal102C₃determines that it may transmit duringtimeslot4, it sends a “request” to transmit to the relay point102B₂on one of thecontrol channel208,210, and212 duringtimeslot2. In accordance with the RUM-based scheme discussed above, other neighboring transmitting nodes may not send a “request” to transmit duringtimeslot2 if their own receiving nodes are less disadvantaged than the relay point102B₂.
• A “request” may take various forms. By way of example, a “request” may include information regarding the timeslot and data channels which the data is to be transmitted (e.g.,timeslot4 and alldata channels206A-206C), and information regarding the data (e.g., the type of data and quality of service expectations, transmission rate information, transmit power, etc.). In addition, a pilot signal may be transmitted with the request. The pilot signal may be transmitted at a known power spectral density or power level. In this way, upon reception of the request and the pilot signal by the relay point102B₂, the appropriate transmission parameters for the data transmission duringtimeslot4 may be determined. Such parameters may include, by way of example, data transmission rate, coding, etc.
• In response to the “request,” the relay point102B₂sends a “grant” to the access terminal102C₃on one of thecontrol channels208,210, and212 duringtimeslot3. The “grant” may include the parameters determined by the relay point102B₂(e.g., data transmission rate, coding, etc.) from the “request” and pilot signal.
• Upon reception of the “grant,” the access terminal102C₃transmits the data on one ormore data channels206A-206C duringtimeslot4. The relay point102B₂may acknowledge receipt of the data by sending an “acknowledgement” on the one of thecontrol channel208,210 and212 during timeslot5 (not shown).
• It will be appreciated that the above request-grant scheme may be implemented as a sliding cycle so that data may be transmitted during every transmit timeslot. By way of example, duringtimeslot1, the relay point102B₂may transmit a RUM on thefirst control channel208 to indicate that it is scheduled to receive a transmission duringtimeslot4, an “acknowledgement” on thesecond control channel210 to acknowledge a transmission received during the previous timeslot (not shown), a “grant” on thethird control channel212 permitting the access terminal102CB₃to transmit duringtimeslot2, and “request” on thethird control channel212 requesting to transmit to the access terminal102C₃duringtimeslot3. The relay point102B₂may also transmit data on one ormore data channels206A-206C intimeslot1 in response to a “grant” received from the access terminal102C₃during the previous timeslot (not shown). The mapping of the control messages to the control channels provided in this example are intended to serve as an illustration only. Various other static and dynamic mapping schemes may be implemented depending on the specific application and the overall design constraints imposed on the system.
• Dynamic mapping of control messages to control channels in the timeslot structure may provide certain advantages in a number of situations. An example will now be presented with reference to FIGS.3 and4A-4B, where a flexible control channel mapping scheme may be used to support asymmetric data flows.
• FIG. 3 is a conceptual diagram illustrating an example of a timeslot structure to support asymmetric data flows between two wireless nodes in a wireless network. In this example, transmissions from a first wireless node to a second wireless node are designated by302A, and transmissions from the second wireless node to the first wireless node are designated by302B. The first wireless node is initially configured to transmit to the second wireless node during odd numberedtimeslots304A,304C, and the second wireless node is initially configured to transmit to the first wireless node during even numberedtimeslots304B,304D. For the purposes of illustration only, and without limitation, the following example will be presented with the first wireless node being the relay point102B₂and the second wireless node being the access terminal102C₃ofFIG. 1. In addition, various control message assignments will be presented for clarity of explanation with the understanding that the control messages may be mapped to different control channels.
• As shown inFIGS. 1 and 3, the time division multiplexing scheme may be dynamically altered to support a change in traffic conditions. By way of example, the relay point102B₂may determine that it has more data to send to the access terminal102C₃than the access terminal102C₃has to send to the relay point102B₂. Under these conditions, the relay point102B₂may temporarily designate several of its receive timeslots as transmit timeslots and the access terminal102C₃may temporarily designate several of its transmit timeslots as receive timeslots. This concept is shown inFIGS. 1 and 3 where the relay point102B₂designatestimeslot6 as a transmit slot and the access terminal102C₃designatestimeslot6 as a receive timeslot.
• FIG. 4A is a conceptual diagram illustrating a more detailed example of a timeslot structure to support asymmetric data flows between two wireless nodes in a wireless network. In this example, the relay point102B₂, which is originally configured to transmit during odd numbered timeslots, decides that it will swaptimeslot4 from a receive timeslot to transmit timeslot. In order to transmit intimeslot4, the relay point102B₂listens for RUMs on thefirst control channel408 oftimeslot1. Here, it should be appreciated that the relay point102B₂is now receiving information during a portion of one of its transmit timeslots. To this end, the timeslots may be defined with guard times before and/or after the control channels to facilitate the relay point102B₂switching from a transmit mode of operation to a receive mode of operation and vice versa.
• Depending on the results of an analysis of the RUMs received on thefirst control channel408, the relay point102B₂may send a “request” to transmit onthird control channel412 to initiate a swap of one or more timeslots. By way of example, the “request” may include a request to transmit during timeslot3 (the relay point102B₂'s normal transmit timeslot) as well as during timeslot4 (a timeslot to be swapped). Thus, in this case, the “request” includes an inherent timeslot swap request. In contrast, in other implementations, the relay point102B₂may inform the access terminal102C₃of a timeslot swap by initially sending a dedicated message (e.g., a request to swap).
• The relay point102B₂may transmit other control information on thethird control channel412. By way of example, the relay point102B₂may transmit a “grant” in response to a “request” by the access terminal102C₃to transmit duringtimeslot2. In addition, the relay point102B₂may transmit an “acknowledgement” in response to data received from the access terminal102C₃during timeslot0 (not shown).
• After receiving the “request” from the relay point102B₂duringtimeslot1, the access terminal102C₃may transmit a “grant” fortimeslot3 or fortimeslots3 and4 on thesecond control channel410 duringtimeslot2. That is, the access terminal102C₃may issue a collective “grant” for multiple timeslots or may issue grants on a timeslot-by-timeslot basis (e.g., when the “requests” are made on a similar basis). In either case, the “grant” received by the relay point102B₂is transmitted on thesecond control channel410.
• Since the access terminal102C₃will not be transmitting data duringtimeslot4, it will not need to transmit a “request” and pilot on thethird control channel412 duringtimeslot2. Instead, the relay point102B₂may transmit a pilot during this period of time on thethird control channel412. Here, it should be appreciated that the access terminal102C₃is now receiving during a transmit timeslot (timeslot2). As discussed earlier, guard times may be provided adjacent thethird control channel412 in the timeslot structure to facilitate the access terminal102C₃switching from a transmit mode to a receive mode and vice versa.
• The access terminal102C₃may also transmit a RUM on thefirst control channel408 in preparation for receiving a data transmission from the relay point102B₂intimeslot5.
• The relay point102B₂may then transmit data on one ormore data channels406A-406B during the requested timeslots (i.e.,timeslots3 and4).
• The relay point102B₂and the access terminal102C₃may continue to provide appropriate signaling to support the swapping of timeslots for as long as the swapping is needed or allowed. By way of example, the relay point102B₂may listen for RUMs associated with contention fortimeslot6 on thefirst control channel408 oftimeslot3. The relay point102B₂may then send on the third control channel412 a pilot and a “request” to transmit duringtimeslots5 and6.
• The access terminal102C₃may use the first andsecond control channels408 and410 duringtimeslot4 to acknowledge receipt of the data fortimeslot3, issue a “grant” fortimeslots5 and6, and transmit a RUM fortimeslot7. Similarly, the access terminal102C₃may use thesame control channels408 and410 duringtimeslot6 to acknowledge receipt of the data fortimeslots4 and5, issue a “grant” fortimeslots7 and8, and transmit a RUM for timeslot9.
• At some point in time, the traffic flow between the relay point102B₂and the access terminal102C₃may be changed back to a symmetric flow.FIG. 4B is a conceptual diagram illustrating an example of a timeslot structure to support a change back to a symmetric data flow between two wireless nodes in a wireless network. For clarity of presentation,FIG. 4B also refers to timeslots1-4. It should be appreciated that the use of similar timeslot numbering is not intended to indicate that such timeslots are referring to the same points in time.
• As shown inFIG. 4B, the request message transmitted by the relay point102B₂on thethird control channel412 duringtimeslot1 includes a “request” only to transmit data duringtimeslot3. In other words, the “request” does not include a request to transmit data duringtimeslot4. The relay point102B₂may also send a RUM on thefirst control channel408 in anticipation of receiving data intimeslot4.
• The access terminal102C₃then transmits on the first andsecond control channels408 and410 during timeslot2 a “grant” associated withtimeslot3, a RUM associated withtimeslot5, and an “acknowledgement” of the data received duringtimeslots0 and1. In addition, the access terminal102C₃transmits on thethird control channel412 during timeslot2 a “request” and pilot so that the access terminal102C₃may transmit data to the relay point102B₂duringtimeslot4. Operations under the original timeslot designation recommence after the access terminal102C₃transmits a “grant,” RUM, and “acknowledgement” on the first andsecond control channels408 and410 duringtimeslot4.
• Another example will now be presented with reference toFIGS. 5 and 6, where a flexible control channel mapping scheme may be used to support jammer avoidance modes of operation.FIG. 5 is a conceptual diagram illustrating an example of a jammer situation that can occur in a home access point (HAP) setting. In this example, anaccess terminal504 jams aHAP502 and vice-versa. More specifically, when theaccess terminal504 is transmitting to theHAP508, theHAP502 cannot receive from theaccess terminal506. Similarly, when theHAP502 is transmitting to theaccess terminal506, theaccess terminal504 cannot receive from theHAP508. In this situation, the twolinks510 and512 can alternate on the channel without losing any timeslots in the transition as shown inFIG. 6.
• FIG. 6 is a conceptual diagram illustrating an example of a timeslot structure to support a jammer avoidance mode of operation. In this example, various control message assignments will be presented for clarity of explanation with the understanding that the control messages may be mapped to different control channels. Referring now toFIG. 6, theHAP502 sends a RUM on thefirst control channel508 duringtimeslot1 to let theaccess terminal504 know that it must back off on control channel usage. The RUM may be a reserved weight setting which requires only energy detection at theaccess terminal504. Upon receiving the RUM, theaccess terminal504 determines that it must backoff from using thethird control channel512 going forward. In this example, intimeslot2, theaccess terminal504 sends in thesecond control channel510 an “acknowledgement” for data received intimeslot1 and signals to theHAP508 that it has received a RUM and will not be able to transmit or receive using the third control channel until it no longer hears a RUM, alternatively for some fixed period or a period that is a function of the weight of the RUM. It also serves as a signal to theHAP508 to use only thesecond control channel510 to signal theaccess terminal504. Intimeslot3, theHAP508 knows that it can only use thesecond control channel510 to acknowledge data sent by theaccess terminal504 intimeslot2. Correspondingly, theHAP502, which sent the RUM, only uses thethird control channel512 to avoid jamming the access terminal's504 reception of control messages on thesecond control channel510. A similar procedure may be applied if theaccess terminal504 wants to send a RUM to make theHAP502 backoff to alternate control channel usage.
• Many other advantages may be obtained through a flexible control channel mapping scheme. By way of example, there could be some wireless nodes that are very disadvantaged in an unplanned deployment. To enable better reliability on control, the control messages could be sent over two control channels to provide more robustness. For higher data rate transmissions or access terminals with less processing capability, control message assignments can be made with “acknowledgements” sent on the third control channel (as opposed to the second control channel) to provide more decoding time. Those skilled in the art will appreciate other advantages and uses for flexible control channel mapping in unplanned deployment, as well as other types of networks.
• To increase flexibility, each control channel may be divided up into sub-channels, or control units. In one example, each control channel comprises an orthogonal frequency division multiplexed (OFDM) symbol which is time division multiplexed within a timeslot. Referring to the timeslot structures described earlier, the first control channel may be a first OFDM symbol, the second control channel may be a second OFDM symbol, and the third control channel may be a third OFDM symbol. Each OFDM symbol may be divided into any number of control units with each control unit comprising any number of tones.
• FIG. 7 is a conceptual diagram illustrating an example of a control channel configured as an OFDM symbol with 512 tones. Each control unit is defined to be 32 tones. Each control unit may be used to send a control message. A field within the control message may be used to determine the type of control message being sent (e.g., request, grant, or acknowledgement). Alternatively, information mapping control message types to control units may be exchanged between the wireless nodes. Several control messages may be carried by a single control unit, with each control message type being assigned to a particular set of tones within the control unit. By way of example, “requests” may be assigned to the first 16 tones of a control unit and “grants” assigned to the second 16 tones in a control unit. Alternatively, or in addition to, a control message may be sent across multiple control units and across multiple control channels. The control units may be of different sizes within a symbol, across symbols, etc. Also, a wireless terminal may transmit on control units of one size and receive on control units of another size.
• The alternative mapping schemes described thus far may be optimized to support communications with several other nodes by dedicating one or more control units to exchanging control messages with each of the other nodes. The one or more control units assigned to support communications with any one of the associated nodes may be static, or dynamically altered to support changing traffic conditions. Additional control units may be assigned to support communications with any associated wireless node to provide more robustness at the expense of reducing the number of associated nodes that can be communicated with at any one time.
• Although an example of a time division multiplexed control channel comprising an OFDM symbol has been presented, those skilled in the art will appreciate that the control channels may be implemented using other multiple access technologies. These multiple access technologies include, by way of example, time division multiple access (TDMA), frequency division multiple access (FDMA), code division multiple access (CDMA), orthogonal frequency division multiple access (OFDMA), or any other suitable multiple access technology now known or developed in the future. Any suitable combination of these multiple access technologies may be used to implement multiple control channels with each control channel having multiple control units.
• FIG. 8 is a block diagram illustrating an example of the functionality of a wireless node. The following descriptive is informative in nature and broadly defines the functionality of each block. Only the pertinent functionality to various concepts described throughout this disclosure will be described. Those skilled in the art will recognize that these functional blocks can provide other functionality that is not described herein. In this example, thewireless node802 includes two functional blocks: anetwork adapter804 and aprocessing system806.
• Thenetwork adapter804 provides both a transmitter and receiver function. The transmitting function includes modulating a carrier with information. The receiver function includes demodulating a carrier to recover information. Thenetwork adapter804 provides various functions such as RF front-end processing, ADC, timing and frequency estimation, channel estimation, turbo coding etc. In summary, thenetwork adapter804 provides the complete physical layer implementation of thewireless node802.
• Theprocessing system806, either alone or in combination with other entities in the wireless node, is configured to implement all functionality above the physical layer. In at least one configuration, theprocessing system806 is configured to use the transmitter and receiver functions of thenetwork adapter804 to support communications with other wireless nodes in the network. Theprocessing system806 supports a timeslot structure having a number of data and control channels with each control channel having a number of control units. In the transmit mode, theprocessing system806 assigns various control messages to the control units and sends data on the data channels. In the receive mode, theprocessing system806 receives various control messages carried by the control units and receives data on the data channels. The control messages include, by way of example, a “request” to transmit, a “grant” in response to a request to transmit, an “acknowledgement,” and a RUM.
• Thewireless node802 may function as an access terminal, access point, relay point, or any combination thereof. Awireless node802 that functions as an access terminal may include auser interface808. Theuser interface808 may include a display, keypad, speaker, microphone, and/or any other suitable interface that enables a user to operate the access terminal. Theuser interface808 is used to control the data that is transmitted and received by theprocessing system806 over a wireless uplink connection maintained by thenetwork adapter804.
• Awireless node802 that functions as an access point includes anetwork adapter804 that is capable of maintaining any suitable number of wireless downlink connections with access terminals and/or relay points, as well as maintain one or more uplink connections to support the backhaul. The uplink connection may be wired or wireless. By way of example, the access point may support a wireless downlink connection to a relay point and a wired uplink connection to another network (e.g., the Internet). In this configuration, theprocessing system806 utilizes the data and control channels in the timeslot structure to efficiently route data between the upstream and downstream wireless nodes.
• Theprocessing system806 may include one or more processors. A processor may be a general purpose microprocessor, a microcontroller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Programmable Logic Device (PLD), logic circuits, discrete hardware components, or any other suitable entity that can perform calculations or other manipulations of information.
• Theprocessing system804 may also include one or more machine-readable media provide data storage and/or to support software applications. Software shall be construed broadly to mean instructions, programs, code, or any other electronic media content whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Machine-readable media may include storage integrated with a processor, such as might be the case with an ASIC. Machine-readable media may also include storage external to a processor, such as a Random Access Memory (RAM), a flash memory, a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable PROM (EPROM), registers, a hard disk, a removable disk, a CD-ROM, a DVD, or any other suitable storage device. In addition, machine-readable media may include a transmission line or a carrier wave that encodes a data signal. Those skilled in the art will recognize how best to implement the described functionality for the processing system.
• FIG. 9 is a block diagram illustrating an example of the functionality of a processing system. In this example, theprocessing system900 includes amodule902 for communicating with another wireless node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, and amodule904 for assigning any one of a plurality of control messages for the data channels to any one of the control units.
• The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

Claims (45)

1. An apparatus for wireless communications, comprising:

a processing system configured to communicate with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, the processing system being further configured to assign any one of a plurality of control messages for the data channels to any one of the control units.

2. The apparatus ofclaim 1 wherein the data and control channels comprise time division multiplexed channels.

3. The apparatus ofclaim 2 wherein each of the control channels comprises an OFDM symbol having a plurality of tones, and wherein each of the control units comprises a portion of the tones for one of the control channels.

4. The apparatus ofclaim 1 wherein one of the control messages comprises a request to transmit.

5. The apparatus ofclaim 1 wherein one of the control messages comprises a grant in response to a transmit request.

6. The apparatus ofclaim 1 wherein one of the control messages comprises an acknowledgement that a transmission has been successfully received.

7. The apparatus ofclaim 1 wherein a first one of the control channels precedes a second one of the control channels in a timeslot, and wherein the processing system is further configured to assign one of the control messages to the second one of the control channels as a function of the processing capability of a transmitting remote node.

8. The apparatus ofclaim 1 wherein the processing system is further configured to, in one timeslot, receive on a first one of the control channels and transmit on a second one of the control channels.

9. The apparatus ofclaim 1 wherein the processing system is further configured to switch between a first mode comprising transmitting on the data channels in every other timeslot and a second mode comprising transmitting on the data channels in consecutive timeslots.

10. The apparatus ofclaim 9 wherein the processing system is further configured to transmit on first and second ones of the control channels in at least one of said every other timeslot in the first mode, and wherein the processing system is further configured to, in at least one of said consecutive timeslots, receive on the first one of the control channels and transmit on the second one of the control channels during the second mode.

11. The apparatus ofclaim 1 wherein one of the control messages comprises a request for a collision avoidance mode of transmission.

12. The apparatus ofclaim 11 wherein the processing system is further configured to transmit said one of the control messages on one of the control channels, the processing system being further configured to communicate all other control messages with a remote node on one or more different control channels during at least one timeslot following said one of the control messages.

13. The apparatus ofclaim 11 wherein the processing system is further configured to receive said one of the control messages on a first one of the control channels, the processing system being further configured to avoid using a second one of the control channels for communicating control messages with a remote node during at least one timeslot following the message.

14. The apparatus ofclaim 1 wherein the processing system is further configured to transmit one of the control messages on at least two of the control channels in one timeslot.

15. A method of communications, comprising:

communicating with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units and each of the control units is capable of carrying any one of a plurality of control messages for the data channels; and

assigning one of the control messages to one of the control units.

16. The method ofclaim 15 wherein the data and control channels comprise time division multiplexed channels.

17. The method ofclaim 16 wherein each of the control channels comprises an OFDM symbol having a plurality of tones, and wherein each of the control units comprises a portion of the tones for one of the control channels.

18. The method ofclaim 15 wherein said one of the control messages comprises a request to transmit.

19. The method ofclaim 15 wherein said one of the control messages comprises a grant in response to a transmit request.

20. The method ofclaim 15 wherein said one of the control messages comprises an acknowledgement that a transmission has been successfully received.

21. The method ofclaim 15 wherein a first one of the control channels precedes a second one of the control channels in a timeslot, and wherein said one of the control messages is assigned to said one of the control units in the second one of the control channel as a function of the processing capability of a transmitting remote node.

22. The method ofclaim 15 further comprising, in one timeslot, receiving on a first one of the control channels and transmitting on a second one of the control channels

23. The method ofclaim 15 further comprising switching between a first mode comprising transmitting on the data channels in every other timeslot and a second mode comprising transmitting on the data channels in consecutive timeslots.

24. The method ofclaim 23 further comprising transmitting on first and second ones of the control channels in at least one of said every other timeslot in the first mode, and, in at least one of said consecutive timeslots, receiving on the first one of the control channels and transmitting on the second one of the control channels during the second mode.

25. The method ofclaim 15 wherein a second one of the control messages comprises a request for a collision avoidance mode of transmission.

26. The method ofclaim 25 further comprising transmitting the second one of the control messages on a first one of the control channels and communicate all other control messages with a remote node on a second one of the control channels during at least one timeslot following the second one of the control messages.

27. The method ofclaim 25 further comprising receiving the second one of the control messages on a first one of the control channels and avoiding using a second one of the control channels for communicating control messages with a remote node during at least one timeslot following the message.

28. The method ofclaim 15 further comprising transmitting said one of the control messages on at least two of the control channels in one timeslot.

29. An apparatus for wireless communications, comprising:

means for communicating with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units; and

means for assigning any one of a plurality of control messages for the data channels to any one of the control units.

30. The apparatus ofclaim 29 wherein the data and control channels comprise time division multiplexed channels.

31. The apparatus ofclaim 30 wherein each of the control channels comprises an OFDM symbol having a plurality of tones, and wherein each of the control units comprises a portion of the tones for one of the control channels.

32. The apparatus ofclaim 29 wherein one of the control messages comprises a request to transmit.

33. The apparatus ofclaim 29 wherein one of the control messages comprises a grant in response to a transmit request.

34. The apparatus ofclaim 29 wherein one of the control messages comprises an acknowledgement that a transmission has been successfully received.

35. The apparatus ofclaim 29 wherein a first one of the control channels precedes a second one of the control channels in a timeslot, the apparatus further comprising means for assigning one of the control messages to the second one of the control channels as a function of the processing capability of a transmitting remote node.

36. The apparatus ofclaim 29 further comprising means for, in one timeslot, receiving on a first one of the control channels and transmitting on a second one of the control channels.

37. The apparatus ofclaim 29 further comprising means for switching between a first mode comprising transmitting on the data channels in every other timeslot and a second mode comprising transmitting on the data channels in consecutive timeslots.

38. The apparatus ofclaim 37 further comprising means for transmitting on first and second ones of the control channels in at least one of said every other timeslot in the first mode and means for, in at least one of said consecutive timeslots, receiving on the first one of the control channels and transmitting on the second one of the control channels during the second mode.

39. The apparatus ofclaim 29 wherein one of the control messages comprises a request for a collision avoidance mode of transmission.

40. The apparatus ofclaim 39 further comprising means for transmitting said one of the control messages on one of the control channels and means for communicating all other control messages with a remote node on one or more different control channels during at least one timeslot following said one of the control messages.

41. The apparatus ofclaim 39 further comprising means for receiving said one of the control messages on a first one of the control channels and means for avoiding using a second one of the control channels for communicating control messages with a remote node during at least one timeslot following the message.

42. The apparatus ofclaim 29 further comprising means for transmitting one of the control messages on at least two of the control channels in one timeslot.

43. A computer-program product for wireless communications comprising:

a machine-readable medium comprising instructions executable by a processing system:

communicate with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units; and

assign any one of a plurality of control messages for the data channels to any one of the control units.

44. An access terminal for wireless communications, comprising:

a processing system configured communicate with a remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, the processing system being further configured to assign any one of a plurality of control messages for the data channels to any one of the control units; and

a user interface configured to enable a user to control communications between the processing system and the remote node.

45. An access point, comprising:

a wireless network adapter configured to support a backhaul for a remote node to a network; and

a processing system configured to communicate with the remote node using a timeslot structure having a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units, the processing system being further configured to assign any one of a plurality of control messages for the data channels to any one of the control units.

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